1. Field of the Invention
The present invention relates to a turbo fan, and more particularly, to a blade structure for a turbo fan.
2. Description of the Background Art
Generally, a blast fan is used for sending air by the rotational force of a disc wheel or a rotor, to a refrigerator, an air conditioner, and/or a cleaner. Specifically, blast fans can be divided into various types, including axial fans, sirocco fans, and turbo fans according to their respective methods for drawing in and discharging air and/or the shape of the fan.
The turbo fan draws in air from a shaft direction of the fan, and discharges the air through a side surface part of the fan in a radial direction. The turbo fan does not include a duct because the air is naturally sucked into the fan and discharged to the outside. This type of fan is typically applied to relatively large sized equipment, e.g., such as ceiling air conditioners.
FIG. 1 is a plan view showing a conventional turbo fan of the background art, and FIG. 2 is a longitudinal, cross-sectional view showing the conventional turbo fan of the background art. As shown in FIGS. 1 and 2, the conventional turbo fan includes a shroud 4; a hub 2 to which a driving device (not shown) is coupled; and a plurality of blades 3 disposed on an outer circumference of the hub 2 in a radial direction and having one side coupled to the shroud 4.
According to the structure described above, the turbo fan 1 includes a suction part 7 for sucking the air on an upper part, a plurality of flow paths 6 for inducing the air which is drawn in through the suction part 7, and a plurality of discharge parts 8 for discharging the air on a side surface part.
The operation of the conventional turbo fan having the above-described structure will be described hereinafter as follows. When the turbo fan 1 is rotated by the driving force of the driving device (not shown), the air is drawn into the suction part 7 by the rotation of the blades 3, and the air which is drawn in through the suction part 7 is discharged to the discharge parts 8 via the flow paths 7.
However, in the blades of the conventional turbo fan, a leading edge on a center part between an end part on the hub side and an end part on the shroud side is formed along a straight line as shown in FIG. 2. A curved part or a bent part may be formed on the hub side in order to get a needed area for the blades.
However, the shape of the blades 3 in the conventional turbo fan is not suitable for xe2x80x9cLxe2x80x9d shape air flow, that is, the air is sucked from the suction part 7 and discharged to the discharge part 8, and therefore noise may be generated by unstable air flows, e.g., such as vortex flow, and the efficiency of the turbo fan is reduced.
The present invention overcomes the shortcomings associated with the background art and achieves other advantages not realized by the background art.
Therefore, an object of the present invention is to provide a turbo fan including a blade having a shape which is able to reduce noise and increase efficiency by preventing unstable air flows such as vortex flow in xe2x80x9cLxe2x80x9d shaped air flows in the turbo fan.
These and other objects are accomplished by a turbo fan comprising a driving device having a rotational shaft; a hub coupled to the rotational shaft of the driving device; a plurality of blades being installed on an outer circumference of the hub and extending in a radial direction; and a shroud coupled to the blades on an opposite side of the hub centering around the blades; wherein a leading edge of each of said blades comprises a coupling part being coupled to the shroud; an extension part extending along a straight line parallel with the rotational shaft and extending away from the hub; and a curved surface part formed having a convex curved surface extending between the extension part and the coupled part, wherein the extension part of the blade extends away from the outer circumferential surface of the hub approximately 40%-60% of a distance (D) measured from the coupling part where the blade and the shroud are coupled to each other to the outer circumferential surface of the hub.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.